1. Field of the Invention
The invention relates to a method for preventing the loss of resistance in a high resistance polysilicon layer resulting from depositing a passivation layer thereover, and more particularly, to a method for maintaining the resistance of the high resistive polysilicon layer to a predetermined level by discharging a plurality of ions or electrons from the high resistive polysilicon layer by performing an annealing process with oxygen plasma and a heat treatment process with nitrogen conditioning gas on a passivation layer deposited on the structure having the high resistive polysilicon layer.
2. Information Disclosure Statement
Generally, in order to increase the resistance of the high resistive polysilicon layer, a method for decreasing the thickness of the polysilicon layer and a method for implanting impurities of As or P into the polysilicon layer, as much as 10.sup.12 -10.sup.14 /cm.sup.2, have been suggested.
However, according to the prior art method, when depositing the passivation layer on the high resistive polysilicon layer of a partially completed semiconductor structure by using a plasma-enhanced chemical vapor deposition process, the plurality of ions or electrons are driven into the high resistive polysilicon layer through a metal layer or a silicon layer positioned as being associated with the polysilicon layer, so that they are trapped into the boundary of the grains of the polysilicon layer, thereby greatly decreasing the resistance of the underlying polysilicon layer.
Therefore, in order to avoid the above mentioned problem, a method has been suggested to maintain the resistance of the polysilicon layer by depositing a silicon nitride Si N layer on the polysilicon layer utilizing a chemical evaporation process. However, according to the process described above, a problem remains in that several additional processes are required. Here, it should be noted that in depositing the passivation layer hydrogen ions occur as a by-product which cannot be avoided during the manufacturing process and which undesirably effect the resistance value of the high resistive polysilicon layer.
Accordingly, it is an object of the present invention to solve the problems set forth above and to provide a method for preventing the resistance of a high resistive polysilicon layer from decreasing due to the deposition of the passivation layer by annealing the passivation layer with oxygen plasma and heating the same with nitrogen conditioning gas to discharge the ions trapped into the boundary of the plurality of the grains in the polysilicon layer.
It is a further object of the present invention to provide a process for preventing the loss of resistance for a high resistive polysilicon layer due to the plurality of ions or electrons trapped into the boundary of the grains of the high resistive polysilicon layer during the depositing process of the passivation layer on the high resistive polysilicon layer.
The preceding objects should be construed as merely presenting a few of the more pertinent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to both the summary of the invention and the detailed description, below, which describe the preferred embodiment in addition to the scope of the invention defined by the claims considered in conjunction with the accompanying drawings.